The analysis of influence of uncertainty factors on mathematical modeling of process of reverse expansion of ammonia in low-speed reciprocating compressor stage. Part 1

Abstract

The paper presents an analysis of the influence on the mathematical modeling of the process of reverse expansion of
ammonia in the area of wet steam, implemented in the working chamber of the reciprocating compressor stage, of such
uncertainty factors as the method for calculating the heat transfer coefficient, the surface temperature of the wall of the
working chamber and the degree of dryness at the beginning of the process of reverse expansion. The mathematical
model is based on the equations of the first law of thermodynamics for a body of variable mass, the equation of state
of a real gas, the Clausius– Clausius and Newton–Richmann equations. The results of the calculation showed that the
instantaneous values of the pressure and temperature of ammonia, as well as its degree of dryness during reverse
expansion in the wet steam region, significantly depend on the chosen method for calculating the heat transfer coefficient.
The process under consideration is also significantly influenced by the temperature of the walls of the compressor working
chamber, in which the compression process is implemented, and the degree of dryness of ammonia at the beginning of
the expansion process.